Audio output debug recording.

media/audio/audio_debug_recording_helper.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "media/audio/audio_debug_recording_helper.h"
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/single_thread_task_runner.h"
+#include "media/audio/audio_manager.h"
+
+namespace media {
+
+AudioDebugRecordingHelper::AudioDebugRecordingHelper(
+    const AudioParameters& params,
+    const AudioFileWriter::CreateCallback& create_audio_file_writer_callback,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+    base::OnceClosure on_destruction_closure)
+    : params_(params),
+      create_audio_file_writer_callback_(create_audio_file_writer_callback),
+      recording_enabled_(0),
+      task_runner_(std::move(task_runner)),
+      on_destruction_closure_(std::move(on_destruction_closure)),
+      weak_factory_(this) {
+  DCHECK(create_audio_file_writer_callback_);
+}
+
+AudioDebugRecordingHelper::~AudioDebugRecordingHelper() {
+  if (on_destruction_closure_)
+    std::move(on_destruction_closure_).Run();
+}
+
+void AudioDebugRecordingHelper::EnableDebugRecording(
+    const base::FilePath& file_name) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(!debug_writer_);
+  DCHECK(!file_name.empty());
+
+  debug_writer_ = create_audio_file_writer_callback_.Run(params_);
+  debug_writer_->Start(
+      file_name.AddExtension(debug_writer_->GetFileNameExtension()));
+
+  base::subtle::NoBarrier_Store(&recording_enabled_, 1);
+}
+
+void AudioDebugRecordingHelper::DisableDebugRecording() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  base::subtle::NoBarrier_Store(&recording_enabled_, 0);
+
+  if (debug_writer_) {
+    debug_writer_->Stop();
+    debug_writer_.reset();
+  }
+}
+
+void AudioDebugRecordingHelper::OnData(const AudioBus* source) {
+  // Check if debug recording is enabled to avoid an unecessary copy and thread
+  // jump if not. Recording can be disabled between the atomic Load() here and
+  // DoWrite(), but it's fine with a single unnecessary copy+jump at disable
+  // time. We use an atomic operation for accessing the flag on different
+  // threads. No memory barrier is needed for the same reason; a race is no
+  // problem at enable and disable time. Missing one buffer of data doesn't
+  // matter.
+  base::subtle::Atomic32 recording_enabled =
+      base::subtle::NoBarrier_Load(&recording_enabled_);
+  if (!recording_enabled)
+    return;
+
+  // TODO(grunell) Don't create a new AudioBus each time. Maybe a pool of
+  // AudioBuses. See also comment in
+  // AudioInputController::AudioCallback::PerformOptionalDebugRecording.
+  std::unique_ptr<AudioBus> audio_bus_copy =
+      AudioBus::Create(source->channels(), source->frames());
+  source->CopyTo(audio_bus_copy.get());
+
+  task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioDebugRecordingHelper::DoWrite,
+                 weak_factory_.GetWeakPtr(), base::Passed(&audio_bus_copy)));
+}
+
+void AudioDebugRecordingHelper::DoWrite(std::unique_ptr<media::AudioBus> data) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (debug_writer_)
+    debug_writer_->Write(std::move(data));
+}
+
+}  // namespace media